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Friday, April 23, 2010

Endoscopic cordectomy

Introduction:

Vocal cord malignancies can be identified at a very early stage because the primary symptom hoarseness of voice prompts the patient to seek medical attention during the early stages of lesion. With the increasing awareness of glottic cancers patients even seek attention during the carcinoma in situ stage itself. Early identification of the problem will help us to resort to conservative surgical procedures with curative intent. Accuracy of diagnosis is further enhanced by the common availability of video laryngoscopes even in the out patient settings commonly. In fact video laryngoscopy has become an out patient procedure, and it picks up vocal cord lesions at a very early stage itself.

Aims of endoscopic cordectomy:

Eradication of malignant process

Preservation of natural function

Can be used to stage the lesion

Advantages of endoscopic cordectomy:

Easily performed procedure

Relatively inexpensive

Preserves voice functions

Indications for endoscopic cordectomy:

T1 glottic carcinomas

Carcinoma in situ with mobile cord where irradiation is contraindicated

Contraindications:

Preoperative stroboscopy will help to rule out deeper tumor extension which is a contraindication for this procedure.

Patients with excessive tumor burden are not ideal candidates for endoscopic resection.

Patients with cervical spine degenerative disorders

Patients with poor mouth opening / retrognathia

Patients with short neck because visualisation of larynx is poor

Positioning of the patient:

Cordectomy / vocal cord stripping is performed ideally under general anesthesia. Patient is placed in supine position with head in 'flexion – flexion' position and intubated with laser safe endotracheal tube. Patient is then shifted to 'flexion – extension' position with cervical flexion and atlanto occipital extension. This position known as Boyce position helps in better visualisation of the anterior commissure area. A Klein Sausser suspension laryngoscope is used to visualize the laryngeal inlet and vocal cords. It is fixed in position with a chest piece. This really frees up both the hands of the surgeon. The entire tumor should be visible through the laryngoscope. Either a microscope or an endscope can be used to visualise the tumor.

Subepithelial injection of saline epinephrine solution using a Brunig's syringe or a butter fly needle will help to determine whether the lesion has spread beyond the lamina propria into the deeper structures like the vocal ligament or thyroarytenoid muscle. In addition to its diagnostic utility this fluid infiltration also serves as a potential heat sink if laser is used. It protects the deeper layers from laser burns.

In patients with carcinoma in situ it is sufficient if only the outer epithelial layer alone is removed and the plane of dissection is confined superficial to the lamina propria. Care should be taken not to expose the vocal ligament as it would entail damage to the gelatinous lamina propria. An intact lamina propria is a must for satisfactory voice production.

If pre op CT scan / stroboscopy reveals deeper invasion of tumor then resection should begin with vestibulectomy. Vestibule is vascular hence laser resection will help in minimizing bleeding. Affected vocal cord should also be removed. This is called classic cordectomy procedure.

Surgery in the anterior commissure area is always fraught with the danger of web formation due to exuberant granulation tissue. This can be avoided by stenting that area or applying mitomycin over the area. Application of mitomycin serves dual purpose, not only it is an anti cancer drug it also reduces the degree of fibrosis.